1. Technical Field
The present invention relates to a valve system for use with a medical device. More particularly, the invention relates to a medical device, such as an introducer, having a hemostatic valve system that allows substantially leak-free passage of a medical interventional device, such as a catheter, through the medical device for insertion into a body vessel.
2. Background Information
Numerous procedures have been developed in modern medicine that require the percutaneous insertion of one or more medical interventional devices into the vascular system. Such procedures include, for example, percutaneous transluminal coronary angioplasty (PTCA), X-ray angiographic procedures, and the like.
The medical interventional devices intended for use in such procedures may be introduced into the vascular system by a variety of known techniques. One widely-used technique is the Seldinger technique. In the Seldinger technique, a surgical opening is made in an artery or vein by a needle, and a wire guide is inserted into the artery or vein through a bore in the needle. The needle is thereafter withdrawn, leaving the wire guide in place. A dilator which is positioned within the lumen of an introducer device is then inserted over the wire guide into the artery or vein. Once the introducer is properly positioned within the artery or vein, the dilator is withdrawn. The introducer may then be utilized in conventional fashion for the insertion therethrough of a variety of types of medical devices, such as catheters, cardiac leads, and the like.
In many cases, an introducer will include one or more hemostatic valve members (also referred to as check valves) for inhibiting leakage of bodily fluids, such as blood, back through the introducer as a medical interventional device is inserted or withdrawn therethrough. The valve members are generally positioned in a housing of the introducer, between a main body portion and an end cap. Typically, such valve members comprise one or more elastomeric disks having one or more slits extending through all or a portion of the disk. On some occasions the valve members may comprise at least one disk having one or more slits, and at least one additional disk having a hole extending through the center of the disk. The slits and/or holes are sized to enable the medical interventional device to pass through the valve member, and to substantially prevent the backflow of fluids through the valve. Hemostatic valves are well known in the medical arts for such purpose, and no further general discussion of the use and function of such valves is necessary to an understanding of the present invention.
Frequently, it is necessary to replace a previously-inserted medical interventional device with another interventional device of a different diameter, or with a different type of device. Such exchanges are normally made over a wire guide, wherein the old device is withdrawn over the wire guide, and the new device is thereafter inserted into the vasculature over the existing wire guide or a newly-inserted wire guide. In many such cases, elastomeric hemostatic valves are provided in an attempt to minimize leakage of blood back through the introducer. Such valves are dependent upon the elasticity of the valve body, and its ability to draw back upon itself to seal any gap created upon insertion or withdrawal of a device through the valve.
Known slitted hemostatic valves generally include one or more slits that criss-cross and span a center portion of the valve, or a hole disposed through the center of the disk. As the interventional device is passed through the center of a slit valve, the slits open outwardly and form one or more generally “V”-shaped openings that are disposed along the outer surface of the interventional device. Such linear-type openings do not form tight seals, and inherently create gaps that permit the leakage of at least some fluid. As a result, hemostatic valve systems often comprise two or three such valve members that are aligned in the valve housing in a manner such that the slit portions are not in axial alignment. Although this arrangement may reduce the amount of leakage compared to the use of a single valve member, the presence of the gaps continues to provide a conduit from which some leakage may occur. Similarly, the various flaps resulting from the slits do not always re-set in the proper manner following passage of the interventional device, thereby creating additional gaps through which fluid may leak.
In addition to the foregoing, when larger slitted valves are utilized, the interventional devices may tear the valve disk beyond the slits upon insertion. This is particularly true when larger size interventional devices are inserted. In such cases, multiple valve disks must be incorporated in order to provide a reasonable degree of confidence that the valve system will continue to provide at least some leakage control. In some cases, the damage to the valve may be so severe, that it may be necessary to incorporate another type of valve, such as a Tuohy-Borst type valve, to the introducer.
Similarly, when smaller slitted valves are utilized, the valves are also subject to tearing when smaller size interventional devices are passed therethrough. Small size interventional devices are often delicate, and possess little hoop strength. When such devices are passed through a small valve member, the thickness and strength of the valve member may cause damage to the delicate structure upon passage therethrough of the interventional device. When small disks are used, the clearance between the opening in the disk and the interventional device can be so slight that it may be difficult to insert and/or withdraw the interventional device. In addition, on some occasions, additional small diameter tubing must be used to keep the valve open so that a catheter may be passed therethrough. When additional equipment is required, such as a small diameter tube or a Tuohy-Borst valve as described, the surgeon's hands, and attention, may be unduly distracted at the very time when all possible focus should be on the major task at hand.
When one or more disks having a hole through the center are used, the disks will only retract back to the size of the center hole following removal of the catheter. As a result, the respective center holes allow leakage once the catheter is removed. Such valves may be satisfactory when there is no need to remove the catheter that seals the opening, however, they are problematic when the catheter is removed and the center opening is created.
It is desired to provide a hemostatic valve system for a medical device that provides an effective seal, and that avoids the problems encountered with prior art seals.